Bentham and Hooker's classification system from 1862 divided plants into three main classes - dicotyledons, gymnosperms, and monocotyledons - based on morphological features. Dicotyledons were further divided into three subclasses of polypetalae, gamopetalae, and monochlamydeae. This system focused on natural relationships between plants rather than artificial systems, and described over 97,000 species. Though it had some limitations like anomalous placements, it was a major natural system and paved the way for modern phylogenetic approaches.
2. CLASSIFICATION OF PLANTS
Artificial Systems Phylogenetic systems
(Based on morphological features)
(Based on evolutionary and
genetic relationship)
Natural systems
(Based on their natural affinities)
3. ARTIFICIAL SYSTEMS
These systems of classification were based on one or few morphological
characters.
a. Theophrastus (370 – 285 BC)
b. Otto Brunfels (1464-1534)
c. Andrea Caesalpino (1519-1603)
d. Joseph Pitton de Tournefort (1656-1708)
e. John Ray (1627-1705)
f. Carolus Linnaeus (1707-1778)
4. NATURAL SYSTEMS
In these systems the organisms are classified on the basis of their natural
affinities (i.e. the basic similarities in the morphology) rather than on a
single character for determining the affinities.
a. A.L. de Jussieu (1748-1836)
b. A.P. de Candolie (1778-1841)
c. Bentham and Hooker’s Classification
5. PHYLOGENETIC SYSTEMS:
Classification based on evolutionary features is known as phylogenetic
system.
a. Engler and Prantl (1884-1930)
b. John Hutchinson (1884-1972)
7. BENTHAM AND HOOKER’S CLASSIFICATION
CLASS-I DICOTYLEDONAE
• Leaves show reticulate venation
• Flowers are tetramerous or pentamerous.
Polypetalae Monochlamydeae
Gamopetalae
8. BENTHAM AND HOOKER’S CLASSIFICATION
SUB-CLASS-I POLYPETALAE
Flowers with free petals come under polypetalae.
The flowers are with distinct calyx and corolla.
THALAMIFLORAE DISCIFLORAE CALCYFLORAE
Flowers with conical or
dome shaped
thalamus
Flowers having prominent
disc shaped thalamus below
ovary
Flowers with cup shaped
thalamus.
Ovary is superior Ovary is superior Ovary is superior or inferior,
sometimes half inferior
6 orders and 34
families
4 orders and 23 families 5 orders and 27 families
9. BENTHAM AND HOOKER’S CLASSIFICATION
SUB-CLASS-II GAMOPETALAE
Flowers with petals , which are either partially or completely fused to one
another .
The flowers are with distinct sepals and petals.
INFERAE HETEROMERAE BICARPELLATE
Flowers are epigynous Flowers having prominent
disc shaped thalamus below
ovary
Flowers with cup shaped
thalamus.
Ovary is inferior Ovary is superior with more
than two carpels
Ovary is inferior, with two
carpels only.
3 orders and 9 families 3 orders and 12 families 4 orders and 24 families
10. BENTHAM AND HOOKER’S CLASSIFICATION
SUB-CLASS-III MONOCHLAMYDEAE
Flowers with single whorl of perianth(sepals and petals not distinguished).
Flowers are incomplete.
Tepals are present in two whorls.
Sometimes, both the whorls are absent.
Includes 8 series and 36 families
11. BENTHAM AND HOOKER’S CLASSIFICATION
CLASS-II GYMNOSPERMAE
• Naked ovules or seeds.
• Ovary is absent.
Gnetaceae Cycadaceae
Conifera
12. BENTHAM AND HOOKER’S CLASSIFICATION
CLASS-III MONOCOTYLEDONAE
• Leaves show parallel venation.
• Flowers are trimerous
• Have fibrous root system
• Has 7 series and 34 families.
13. BENTHAM AND HOOKER’S CLASSIFICATION
o SALIENT FEATURES:
1. It is a classification of only the “seed plants” or phanerogams.
2. They described 97,205 species of seed plants belonging to 7,569 genera of202
families starting from Ranunculaceae up to Gramineae.
3. They classified all the seed plants into 3 groups or classes i.e. Dicotyledons (165
families), gymnosperms (3 families) and monocotyledons (34 families).
4. Monocotyledons were described after the dicotyledones.
14. BENTHAM AND HOOKER’S CLASSIFICATION
o SALIENT FEATURES:
5. The dicotyledons were divided into 3 Divisions (Polypetalae, Gamopetalae and
Monochlamydeae) and 14 series. Each series again divided into cohorts (modern
orders) and cohorts into orders (modern families).
6. The authors did not mention anything about the origin of the angiosperms.
7. Creation of the Disciflorae, a taxon not described by the earlier taxonomists.
8. Among the Monochlamydeae, major taxa, like the series, were divided on the
basis of terrestrial and aquatic habits.
15. BENTHAM AND HOOKER’S CLASSIFICATION
o MERITS :
1. Bentham and Hooker’s classification is the most natural system, based on
actual examination of specimens.
2. The description of plants is quite accurate and reliable.
3. The flora describes geographical distribution of species and genera.
4. The generic descriptions are complete, accurate and based on direct
observations.
16. BENTHAM AND HOOKER’S CLASSIFICATION
o MERITS :
5. Larger genera have been divided into sub genera, each with specific number of
species.
6. Although this system is natural, most of the aspects of this system show affinity
to modern concepts of evolution.For example-dicots begin with the order Ranales
which are now universally considered as to be the most primitive angiosperms.
7. Placing of monocots after the dicot is again a natural one and according to
evolutionary trends.
8. As it is is easy to follow, it is used as a key for the identification of plants in
Kew herbarium and several other herbaria in the world.
9. The placing of gamopetalae after polypetalae is justified since union of petalsis
considered to be an advanced feature over the free condition.
17. BENTHAM AND HOOKER’S CLASSIFICATION
o DEMERITS :
1. Keeping gymnosperms in between dicots and monocots is anomalous.
2. Subclass monochlamydeae is quite artificial.
3. Placing of monochlamydeae after gamopetalae does not seem to be natural.
4. Some of the closely related species are placed distantly while distant species are
placed close to each other.
18. BENTHAM AND HOOKER’S CLASSIFICATION
o DEMERITS :
5. Certain families of monochlamydeae are closely related to families in
polypetalae, e.g. Chenopodiaceae and Caryophyllaceae.
6. Advanced families, such as Orchiadaceae have been considered primitive in
this system by placing them in the beginning. Placing of Orchidaceae in the
beginning of monocotyledons is unnatural as it is one of the most advanced
families of monocots. Similarly, Compositae (Asteraceae) has been placed near
the beginning of gamopetalae which is quite unnatural.
7. Liliaceae and Amaryllidaceae were kept apart merely on the basis of
characters of ovary though they are very closely related.
8. There were no phylogenetic considerations
![CLASSIFICATION OF PLANTS
[BENTHAM AND HOOKER]
BY : S. DASH](https://image.slidesharecdn.com/benthamhooker-210522170053/85/Classification-of-Plants-Bentham-Hooker-1-320.jpg)
